Valve

ABSTRACT

Embodiments relate to valves comprising a member such as a plate or poppet, that is moveable relative to a stationary seat. The state of the member may be maintained against opposing forces with relatively little expenditure of energy. According to one embodiment, a poppet displaced from seating in the valve seat, may be held in position against opposing forces tending to close the valve, until a desired flow of gas through the valve has taken place. The poppet may then be released as desired, such that those opposing forces serve to passively close the valve. The valve may be secured in position utilizing mechanical, magnetic, electromagnetic, pneumatic, electrostatic, or hydraulic approaches. Valve embodiments may be particularly suited to controlling gas flows for compression and/or expansion in an energy storage system.

CROSS-REFERENCE TO RELATED APPLICATIONS

The instant patent application claims priority to and is a continuationapplication of U.S. Nonprovisional patent application Ser. No.13/552,580 filed Jul. 18, 2012, which claims priority to U.S.Provisional Patent Application No. 61/509,511 filed Jul. 19, 2011 andU.S. Provisional Patent Application No. 61/529,543 filed Aug. 31, 2011,all of which are incorporated by reference in its entirety herein forall purposes.

BACKGROUND

Valves allowing the selective flow of gas or gas-liquid mixtures, finduse in a variety of applications.

SUMMARY

Particular embodiments relate to a valve structure for use in flowinggas or gas-liquid mixtures. In certain embodiments the valve comprises afixed housing having port(s) present therein. A plate having opening(s)is moveable relative to the fixed housing. Motion of the plate resultingin alignment of the respective ports and openings, permits the rapidmovement of a gas or a gas-liquid mixture through the valve, with lowresistance and reduced coalescence of any entrained liquid droplets.Particular embodiments relate to rotary valves employing rotation of theplate relative to the housing. The valve may be actively controlled.

Certain embodiments relate to fluid flow valves comprising a member(such as a poppet or plate) moveable relative to a stationary seat,where the state of the member may be maintained against countervailingforces with relatively small expenditure of energy. In one embodiment, apoppet displaced from seating in the valve seat, may be held in thatposition against opposing forces tending to close the valve, until adesired flow of gas through the valve has taken place. The poppet maythen be released as desired, such that those opposing forces serve topassively close the valve. The moveable member may be secured inposition against the countervailing forces utilizing mechanisms operablebased upon mechanical, magnetic, electromagnetic, hydraulic, pneumatic,and/or electrostatic principles. Valve embodiments may be particularlysuited to control flows of gases for compression and/or expansion in anenergy storage system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows a simplified view of an embodiment of a cylinder deviceincluding an inlet valve, acting as a gas expander.

FIG. 1B plots valve area versus crank angle for an idealized inlet valvefor the expander of FIG. 1A.

FIG. 2A shows a simplified perspective view of one valve embodiment.

FIG. 2B shows a simplified cross-sectional view of the embodiment ofFIG. 2A.

FIG. 2C is a generalized plot of valve area versus crank angle for thevalve embodiment of FIG. 2A.

FIGS. 2DA-2DC are plots of valve area versus crank angle for variousembodiments.

FIG. 3A shows a simplified perspective view of an alternative valveembodiment.

FIG. 3B shows a simplified cross-sectional view of the embodiment ofFIG. 3A.

FIG. 3C is a generalized plot of valve area versus crank angle.

FIG. 4A shows a simplified perspective view of another valve embodiment.

FIG. 4B shows a simplified cross-sectional view of the embodiment ofFIG. 4A.

FIG. 4C is a generalized plot of valve area versus crank angle.

FIG. 4D is a generalized plot of valve area versus crank angle.

FIG. 5A shows a simplified perspective view of another valve embodiment.

FIG. 5B shows a simplified cross-sectional view of the embodiment ofFIG. 5A.

FIG. 5C is a generalized plot of valve area versus crank angle.

FIGS. 6A-I show various active valve actuation schemes.

FIGS. 7AA-7CC show various gas flow valve actuation approaches.

FIG. 8 shows a simplified view of an embodiment of an energy storagesystem.

FIG. 9 shows a simplified view of an alternative energy storage systemembodiment.

FIG. 9A shows various basic operational modes of the system of FIG. 9.

FIGS. 9BA-BF show simplified views of the gas flow paths in variousoperational modes of the system of FIG. 9.

FIGS. 10A-I show various views of an alternative rotary gas flow valveembodiment.

FIGS. 11A-D show views of an embodiment of a compression releasemechanism.

FIGS. 12A-I show various views of an alternative embodiment of a rotaryvalve.

FIGS. 13A-B are diagrams of an embodiment of a valve control system.

FIG. 14 shows a simplified view of a control loop for active valvecontrol.

FIG. 15 shows a simplified view of a computer system suitable for use incontrolling valve embodiments.

FIG. 15A is an illustration of basic subsystems in the computer systemof FIG. 15.

FIGS. 16A-D show operation of a valve embodiment during a compressioncycle in a cylinder housing a reciprocating piston.

FIGS. 17A-17E show operation of the valve embodiment of FIGS. 16A-Dduring a corresponding expansion cycle.

FIG. 17F plots piston position versus crank angle during the expansioncycle shown in FIGS. 17A-E.

FIG. 17G plots pressure versus volume for the expansion cycle of FIGS.17A-E.

FIGS. 18A-C show a valve embodiment utilizing a mechanical mechanism tomaintain valve state against countervailing forces.

FIG. 19A-C show a valve embodiment utilizing a hydraulic mechanism tomaintain state against countervailing forces.

DESCRIPTION

U.S. Patent Publication No. 2011/0115223 (“the '223 Publication”)describing an energy storage and recovery system employing compressedgas as an energy storage medium, is incorporated by reference in itsentirety herein for all purposes. Certain apparatuses and methodsdescribed in the '223 Publication employ a reversible mechanismcomprising a reciprocating piston within a cylinder, to compress gas andin turn recover energy from expanding gas. Valving regulates the flow ofgases into and out the cylinder.

Rotary Valve

FIG. 1A shows a simplified view of an embodiment of a cylinder device100 having piston 102 disposed therein. Piston 102 is in physicalcommunication with crankshaft 104 via piston rod 106.

The cylinder device may act as a compressed gas expander. In particular,inlet valve 108 may be actuated to allow compressed gas from acompressed gas source (such as a storage tank or a compressor) to beginto flow into cylinder device 100 when piston 102 is in the Top DeadCenter (TDC) position corresponding to a crank angle of 0 degrees of thecrankshaft. The expansion of this compressed gas within the cylinderdevice drives the piston and piston rod, allowing useful work to berecovered (in some cases in the form of electricity produced by agenerator).

In the highly simplified case shown in FIG. 1A, the inlet valve 108 ismaintained in the open position through the crank angle reaching 180degrees, corresponding to the Bottom Dead Center (BDC) position of thepiston within the cylinder. As discussed at length in the '223Publication, it may be desirable to close the inlet valve prior toreaching BDC. It may also be desirable to open the inlet valve earlieror later than TDC. The optimum valve timing depends on many factors in apractical machine, including the considerations for active valveactuation discussed below in connection with FIGS. 6A-I. Thus, FIG. 1Ais being provided for purposes of illustration only, and therelationship between valve actuation and crank angle is not limited tobeing as shown in that figure.

Ideally, the inlet valve 108 would exhibit the profile shown in FIG. 1B.That is, the valve would shift from being fully closed (valve area=0) tobeing completely open (valve area=A) at TDC (crank angle=0°), and thenshift from being fully open (valve area=A) to being fully closed (valvearea=0) at BDC (crank angle=180°).

Such an idealized valve actuation profile would afford extremely precisecontrol over the volumes of compressed gas admitted to the cylinder andexpanded. In reality however, such instantaneous valve actuation isdifficult to achieve.

Instead, an actual valve would operate over some amount of time(characterized here in terms of crank angle) to move between open andclosed positions. Accordingly, embodiments of valve structures may allowcontrol over valve actuation to determine the shape of opening andclosing profile shown in idealized form in FIG. 1B.

FIG. 2A shows a perspective view of one embodiment of a valve. FIG. 2Bshows a simplified cross-sectional view of the embodiment of FIG. 2A.

Valve 200 comprises a circular housing 202 defining a port 204 in ashape of a truncated arc segment, occupying an amount of arc designatedas theta (A). The port 204 defines the fully open area (A) of the valve.The housing 202 and the corresponding port 204 are fixed in place.

Valve 200 further comprises a circular plate 206 overlying the housing202. The circular plate defines an opening 208 in the shape of atruncated arc segment occupying an amount of arc designated as alpha(α).

The plate 206 is rotatable in the clockwise direction (for example by ashaft) relative to the fixed housing. In this particular embodiment, theangle of rotation of the plate (plate angle), corresponds to the crankangle.

Rotation of the plate 206 resulting in complete alignment of the opening208 with the port 204, opens the valve and allows the passage of gas.Rotation of the plate 206 resulting in no overlap between the openingand the port, closes the valve and blocks the passage of gas. Rotationof the plate resulting in less than complete alignment between theopening and the port, produces a partially open valve state allowingsome passage of gas.

Specifically, FIG. 2C is a generalized plot of valve area versus crankangle for the valve embodiment of FIG. 2A. Again, in this particularembodiment the crankshaft angle corresponds to the angle of the rotatingplate. This figure shows various features of the curve, in relation tothe sizes (θ, α) of the ports and openings.

FIG. 2C also shows that the time of opening of the valve may be offsetby some amount or phase shift, here designated by the greek letter phi(φ). This phase shift corresponds to the location of the leading edge ofthe opening relative to the leading edge of the port, at the crank angleof zero (0). Where the leading edge of the opening is exactly alignedwith the edge of the port at a crank angle of zero, then φ=0.

The generalized plot of FIG. 2C may be better understood with referenceto some specific examples. For example, FIG. 2DA compares the plot ofFIG. 1B for an idealized valve, with the valve of FIG. 2A where θ=α=90°,and φ=0.

The particular plot of FIG. 2DA is in the shape of a triangle, owing tothe exact same size of the port (θ) and plate opening (α). In otherwords, due to these relative sizes, there exists complete overlapbetween the port and opening (and a full valve area of A) for only oneinstant of crank angle.

A change in the size of the port and/or opening, will affect the profileof the curve. For example, FIG. 2DB shows a plot wherein the sizes ofboth the port and opening have been reduced by the same amount(θ=α=67.5°), thereby resulting in a smaller peak valve area A′. Again,the plot here is of a triangle, owing the exact correspondence in sizebetween the port and the opening.

FIG. 2DC shows a plot characteristic of a change in the size of only oneof the port or the opening. Here θ or a has been reduced from 90° to67.5°. This plot is in the shape of a plateau, with the flat portionreflecting a prolonged duration of the valve in the fully open stateowing to the greater size of one of the port or opening relative to theother. Note that this fully open state is A′, corresponding to a smallerport or opening angle of only 67.5°.

In this and other embodiments described herein, the correlation betweenmovement of the plate/opening and movement of crank may be fixed. Thatis, the plate/opening rotates predetermined amount based upon the crankangle. Such embodiments may be realized utilizing a physical connection(for example a mechanical, hydraulic, or other type linkage) presentbetween the valve and the crank to coordinate their action. Suchconfigurations may offer the potential benefits of fast response andrelative simplicity of structure.

FIG. 3A shows a simplified perspective view of an alternative valveembodiment which may employ a fixed relation between crank angle andamount of valve area. The specific embodiment of FIG. 3A includes twoports 306 that each occupy no more than 45°, and which are located 180°apart on the fixed housing 308. The rotating valve plate 302 alsofeatures two openings 304 occupying no more than 45° and located 180°apart. FIG. 3B shows a simplified cross-sectional view of the embodimentof FIG. 3A.

The valve plate of the embodiment of FIGS. 3A-B is also configured torotate a fixed amount relative to the crank, here: plate angle (mod180°)=(crankshaft angle−φ)/2. This relationship means the valve platerotates at one-half the speed of the crank. FIG. 3C accordingly shows ageneralized plot of valve area versus crank angle for the valveembodiment of FIGS. 3A-B.

A valve configuration featuring a valve plate with more than oneopening, may offer certain benefits. One benefit of having the rotaryvalve turn at the compressor speed divided by an integer not less thantwo, is that the valve plate is now radially symmetric and vibration issignificantly reduced. In addition, as in the embodiment of FIGS. 3A-C,having the rotary valve turn at half compressor speed reduces the powerconsumed operating the valves. This can improve the efficiency andcost-effectiveness of the device.

The embodiment of FIGS. 3A-C also reduces maintenance costs. Inparticular, symmetrical positioning of the openings in the valve plate,balances the plate during rotation and thereby reduces wear. Wear isalso reduced by the need to rotate the valves less quickly.

While not explicitly shown, changing the size of the ports and/oropenings of such multi-port/opening embodiments can result in plots ofvalve area vs. crank angle, that are similar to those shown in FIGS.2DA-DC.

Still other valve embodiments are possible. For example, FIGS. 4A-B showsimplified exploded and cross-sectional views of another rotary valvestructure, in which valve area can be changed dynamically.

Similar to the embodiment of FIG. 3_, the valve 400 of FIG. 4_ comprisesa circular fixed housing 402 defining two ports 404 that each occupyapproximately 45° of arc. The ports 404 define the fully open area (A)of the valve. The housing 402 and the corresponding ports 404 are fixedin place.

Valve 400 further comprises a circular plate 406 overlying the housing402. The circular plate defines two openings 408 that each also occupyapproximately 45° of arc.

Again, the valve plate 406 is rotatable in the clockwise direction (forexample by a shaft) relative to the fixed housing. Rotation of the plate406 resulting in complete alignment of the openings 408 with the ports404, opens the valve and allows the passage of gas. Rotation of theplate 406 resulting in no overlap between the openings and the ports,closes the valve and blocks the passage of gas. Rotation of the plateresulting in less than complete alignment between the openings and theports, results in a partially open valve state.

The valve embodiment of FIGS. 4A-B differs from the embodiment of FIGS.3A-B, however, in the inclusion of a fixed aperture 420 having cutouts421, that is imposed between the rotatable plate and the fixed housing.Specifically, the fixed aperture is selectively rotatable in front ofthe port to effectively change the area of the valve.

While the embodiment of FIGS. 4A-B shows the fixed aperture as beingpositioned between the rotating plate and the housing, this is notrequired. Alternative embodiments could position the fixed aperturedistal from the chamber side, on the other side of the valve plate,thereby potentially reducing an amount of dead volume attributable tostructure of the valve.

Details of the operation of the operation of the valve of FIGS. 4A-B,may be understood with reference to FIGS. 10A-10I. Specifically, asshown in those figures, in a fully closed position an edge of the fixedaperture rests against a raised surface of the fixed housing in order toblock an undesired leak pathway. FIGS. 10A-10I are discussed in detailfurther below.

FIG. 4C plots the profile of valve area vs. crank angle for theconfiguration of FIGS. 4A-B, with the fixed aperture rotated to occludeapproximately 22.5° of the arc of the port. This results in reduced areafor the valve, indicated in FIG. 4C as area A″.

Moreover, actuation of the fixed aperture has also altered the shape ofthe valve area/crank angle profile. In particular, the profile haschanged from a triangle to a trapezoid. This reflects the fact that theeffective shape of the port no longer exactly matches the full areaoffered by valve plate opening, so that even complete overlap betweenthe two yields only the reduced valve area A′ (but over an extendedrange of crank angles−the ‘plateau’ in this curve).

While the plot of FIG. 4C shows a phase shift (φ) of zero, this is notrequired. For example, in certain embodiments the phase shift may bechosen to open the valve at TDC for suction, or at BDC for discharge.

Moreover, the phase shift might be advanced (or retarded) from thoseparticular positions in order to optimize flow through the cylinder. Forexample, opening the valve earlier when the piston is moving slowlyrepresents a small loss, but the valve may be opened longer (assumingthe same closing time), thereby making the effective area larger for anet improvement.

The inclusion of the fixed aperture feature disclosed in the embodimentof FIGS. 4A-B, changes the performance of the valve in a non-ideal way.In particular, the change in valve duration is accompanied by areduction in valve area.

In certain applications however, it may be desirable to effect a changein valve duration while maintaining the largest valve area possible.FIGS. 5A-C accordingly show an alternative embodiment of a valvestructure that is capable of achieving this goal.

In particular, the valve embodiment of FIGS. 5A-C also includes a movingaperture mechanism for controlling the effective area (α) of therotating opening, so that it matches the effective area (θ) of the port(as occluded by the fixed aperture). Being able to vary both theta andalpha in this manner, allows varying of the valve duration whilemaintaining a large valve area. This happens when theta and alpha areequal.

Specifically, FIGS. 5A-B show simplified exploded and cross-sectionalviews of the valve embodiment. As with the earlier embodiments, valve500 comprises a circular housing 502 defining ports 504, each occupyingapproximately 45° of arc. The ports 504 define the fully open area (A)of the valve. The housing 502 and the corresponding ports 504 are fixedin place.

Valve 500 further comprises a circular plate 506 overlying the housing502. The circular lower plate defines openings 508 that also each occupyapproximately 45° of arc.

Again, the plate 506 is rotatable in the clockwise direction (forexample by a shaft) relative to the fixed housing. Rotation of the plate506 resulting in complete alignment of the openings 508 with the ports504, opens the valve and allows the passage of gas. Rotation of theplate 506 resulting in no overlap between the openings and the ports,closes the valve and blocks gas passage. Rotation of the plate resultingin less than complete alignment between the openings and the ports,produces a partially open valve state allowing some passage of gas.

The valve 500 also includes a fixed aperture as described in theembodiment of FIGS. 4A-C. In particular this fixed aperture 520including cutouts 521, is present between the rotatable plate and thefixed housing. Specifically, the fixed aperture is selectively rotatablein front of the port to effectively reduce its area.

Unlike the previous embodiments, the valve 500 further includes a movingaperture 530. The moving aperture spins together with the valve plate,but can also be rotated relative to the valve plate to occlude part orall of the openings thereof. A raised control surface 532 of the movingaperture projecting into and moveable within the opening 508 of thelower plate, serves to block a possible leakage pathway in the completevalve occlusion state.

Details of the operation of the operation of the valve of FIGS. 5A-C,may be understood with reference to FIGS. 12A-I, which are discussed indetail below. While the embodiment of FIGS. 12A-I shows the fixedaperture as being positioned between the rotating plate and the fixedhousing, this is not required. Alternative embodiments could positionthe fixed aperture distal from the chamber side (for example on theother side of the valve plate and moving aperture), thereby potentiallyreducing an amount of dead volume attributable to valve structure.

Performance of the valve embodiment shown in FIGS. 5A-5B may befavorably contrasted with that shown in FIGS. 4A-C, with reference to anexample where the valve is to be open over 135° of crank angle.

In a valve embodiment where the value of alpha is fixed (for example at45° as in FIGS. 4A-C), theta would need to be set to 22.5° degrees inorder to achieve the desired opening over 135° of crank angle. The areaplot for such an embodiment is shown in FIG. 4D, where the valve arearamps up between crank angles of 0-45°, remains constant over 45-90°interval of crank angle, and then ramps down between crank angles of90-135°.

In contrast FIG. 5C is the area plot for a corresponding valveembodiment that can vary both theta and alpha. In particular wheretheta=alpha=33.75°, the valve would ramp up between 0-67.5° and thenramp down from 67.5-135°. Such valve performance increases the effectivearea by 12.5%, as is indicated in the dashed line in FIG. 4D forcomparison.

Similarly, if a valve opening duration of 100° is desired, varying bothalpha and theta yields an effective area that is nearly 2.8× greaterthan that of the corresponding valve in which only theta is varied. If avalve open time of 180° or less is desired, being able to reduce alphato below 45° may be useful.

Embodiments described so far may relate to valves having a fixedrelationship between crank angle and valve area. However this is notrequired, and alternative embodiments may not necessarily employ fixedcorrelation between valve movement and crank motion.

For example, certain embodiments could include sensor(s) allowing therelative crank position to be indexed. Specifically, a sensor coulddetect the relative position of the crank and in turn send electricalsignals to a motor (such as a stepper motor) that is responsible forcontrolling movement of the valve elements.

Embodiments allowing variation in valve state relative to crank angle,may offer benefits by allowing flexibility between movement of the crankand corresponding movement of the valve. For example, theopening/closing profiles of the valve embodiments of FIGS. 2A-B and 3A-Bare correlated to crankshaft rotation according to the respectiveprofiles in FIGS. 2C and 3C. As described in the '233 Publication,however, in certain applications it may be desirable to change valveactuation to deviate from these profiles.

For example, FIGS. 6A-C show closure of the gas flow valve 637 in anexpansion cycle, prior to the reciprocating piston reaching BDC. Thisvalve timing serves to limit an amount of compressed gas (V₀) admittedto the cylinder, to less than the full volume of the cylinder. Inlet ofsuch a reduced quantity (V₀) of compressed gas can desirably enhance anefficiency of energy recovery, by lowering a differential at BDC betweenthe pressure of gas expanded within the chamber, and the pressure of thelow pressure side. This low pressure side can be of a successivelower-pressure stage (in the case of a multi-stage expander), or can beof an outlet (in the case of a final stage or single-stage expander).

Active valve actuation can also enhance the power recovered from theexpansion of compressed gas. For example, FIGS. 6D-F show closure of thegas flow valve 637 in an expansion cycle. Here, this valve timing servesto admit an amount of compressed gas (V₊) to the cylinder, that isgreater than (V₀). The expansion of a larger volume of gas results inthe piston being driven downward with higher energy, resulting in agreater amount of power being output from the system.

Active valve actuation to control power output during expansion, may beparticularly relevant to stand-alone energy storage units that are notconnected to the grid. Such control can allow maintenance of electricaloutput at a fixed frequency while the load and gas pressure arechanging. In a technique known as “cut-off”, active valve control haspreviously been used to control steam engines, where steam pressure andload vary. According to certain embodiments, a simple speed sensorfeedback could be used for such valve control.

A larger power output from expansion may occur at the expense ofefficiency, as the inlet compressed gas expands to a pressure greaterthan that of the low pressure side. This can reduce system efficiency bynot extracting the maximum amount of energy from the compressed gas.This can also reduce system efficiency by creating a pressuredifferential at the end of the expansion stroke.

In a manner analogous to that described above for expansion, activevalve actuation can also enhance the efficiency of a gas compressioncycle. For example, as shown in FIGS. 6G-H, during the addition of gasand compression, the valve 638 between the cylinder device 622 and thestorage unit 625 (high pressure side) remains closed, and pressurebuilds up within the cylinder.

In conventional compressor apparatuses, accumulated compressed gas maybe contained within the vessel by a check valve, that is designed tomechanically open in response to a threshold pressure. Such use of theenergy of the compressed air to actuate a check valve, detracts from theefficiency of energy recovery by consuming energy to perform work.

By contrast, as shown in FIG. 6I, embodiments of the present inventionmay actively open outlet gas flow valve 638 under desired conditions,for example where the built-up pressure in the cylinder matches or isnear the pressure on the high pressure side. In this manner, energy fromthe compressed air within the cylinder is not consumed by the valveopening process, and efficiency of energy recovery is enhanced.

Active control of a gas inlet valve during a compression cycle, canserve to increase the flow rate of compressed gas. For example, wherethe compressed gas supply is low but there exists a high expected needfor stored energy (e.g., the night preceding onset of a forecasted heatwave), the timing of opening of an inlet valve may be prolonged to admitmore gas than can be compressed with the greatest efficiency. Such amode of operation results in a higher flow rate of compressed gas,allowing the compressed gas storage unit to be replenished more rapidlyin order to meet the expected future demand.

A larger flow rate may take place at the expense of efficiency, ascompression results in a greater pressure differential between thechamber and high pressure side at the conclusion of the compressionstroke. Efficiency of the compression process could also be eroded by anincrease in temperature of the gas being compressed to a higherpressure.

Active valve actuation schemes may facilitate active valve actuation toachieve one or more of the aims described in connection with FIGS.6A-6I.

FIG. 7AA plots valve plate angle in degrees versus time for anon-actively controlled embodiment of FIGS. 3A-B, where the valve platesimply rotates at a fixed amount relative to crank angle according tothe relation: valve plate angle (mod 180°)=(crankshaft angle−φ)/2. FIG.7AB plots the velocity (shaft speed) over time of the motor responsiblefor actuation of the valve, showing a constant angular velocity. Themotor speed may be controlled by a voltage, a current, a pulse width, ora frequency (such as with a stepper motor). A digital control signal mayalso be employed.

In contrast to such a passively controlled valve embodiment, by varyingthe speed of the valve plate during its rotation, the duration of fulloverlap between the valve plate opening and the port, can be enhanced.Specifically, the solid line in FIG. 7BA plots plate angle (again indegrees) versus time, for one embodiment of an actively controlledvalve. Also shown along the X-axis in FIG. 7BA is the crank angle.

Over a first time period (to T_(T)), the valve plate is rotated atvariable high speed to achieve full overlap between the port and thevalve plate opening (at min(θ,α)). Over a second time period (tot₃−T_(T)), the valve plate is rotated at variable lower speed to prolonga duration of this full overlap between the port and plate valve thatconcludes at max(θ,α).

Over a third time period (to t₃), the valve plate is again rotated atvariable higher speed to bring the valve to a fully closed state at θ+α.The relatively higher speed is continued past t₃ and reduced to arelatively lower speed at t₄.

Over a fourth time period (to t₅), the valve plate is rotated atvariably lower speed. Over a fifth time period (to T), the valve plateis again rotated at variably higher speed in order to bring the valvespeed to a relatively higher speed at the start of the next cycle,corresponding to a half rotation of the plate (180°). Note that thevalve is closed between t₃ and T. The speeding up and slowing down ofthe valve plate during the first half of the cycle increases theeffective area of the valve while open. The speed variations during thesecond half of the cycle are to match conditions at the beginning andend of the first half cycle and to match the desired speed.

FIG. 7BB plots angular velocity over time of the motor (such as astepper motor) responsible for actuation of the valve. FIG. 7BB alsoplots along the X-axis, the quantity delta (Δ), where Δ=(ψ−φ)/2, with ψbeing the crank angle, and φ being the phase shift.

FIG. 7BB shows a plot of velocities varying between V_(MAX) and lowervelocities V₁ and V₂, in order to achieve the desired valve actuationprofile. Note that velocity ramp-up and ramp-down rates may bedifferent. Because the valve closed time is different from the valveopen time, the velocity V₂ may typically be lower than the velocity V₁.

While effective to actively control the valve, the scheme of FIGS. 7BA-Coffers complexity in the application of velocity control signals thatvary over time. In particular, the hardware required to accommodate suchvariable speed performance may be costly to obtain and maintain.

Accordingly, FIGS. 7CA-CC show an alternative active control schemecalling instead for the application of piecewise constant velocitycontrol signals. In this particular embodiment, active control over thevalve feeds a low-pass filter before driving the motor, allowing acontrol signal at only two velocities (low: V₁; and high: V_(MAX)).

In particular FIG. 7CA plots valve plate angle versus delta, which takesthe form of a series of lines. The slopes of these lines may be relatedto the quantity rho (ρ), which is the value of delta (Δ) correspondingto the plate angle of min(θ,α). For example the slope (S₁) of the linefrom a plate angle of 0, may be expressed by the following relation:

S₁≡min(θ,α)/ρ=V_(MAX)*T/180°, where T is the period of one crankrevolution and V_(MAX) is the maximum allowable valve plate speed (indegrees/second).

FIG. 7CB plots the varying signal of angular shaft velocity over time.Application of a low pass filter to this signal, helps to avoidattempting to accelerate or decelerate the motor faster than isphysically possible. As described below in detail in connection withFIG. 13, such low pass filtering can be accomplished electronically inthe hardware responsible for controlling the valve.

FIG. 7CC accordingly shows the resulting plot of velocity versus time,indicating the sequential application of only two constant velocities(V_(MAX), V₁) to the motor in order to achieve active valve actuation.

FIGS. 13A-B are diagrams showing a valve control circuit according toone embodiment. FIG. 13A is a simplified diagram of a physical circuitthat may be used to control a rotary valve. This figure shows low-levelcontrol within each valve. The particular physical circuit 1300 includesthree small controllers or processors: two microcontrollers 1302, 1304,and a digital signal processor (DSP) 1306. Alternatively, functionalitycould be implemented in a single controller.

The encoders 1307, 1309 shown in FIG. 13A are quadrature encoders thatproduce three outputs. These outputs are two quadrature outputs, and anindex pulse.

FIG. 13B shows a functional block diagram of one embodiment of a controlloop implemented by the rotating plate DSP 1306 in FIG. 13A. Variablefrequency oscillator (VFO) 1312 is nominally set to drive the rotatingplate motor at one-half the speed of the crankshaft.

This speed of the rotating plate motor is modified in a phase lockedloop (PLL) configuration. The crank angle offset by the desired phaseangle, is compared with the rotating plate angle. Here the rotatingplate angle is scaled by two, because the rotating plate rotates at halfthe speed of the crankshaft. This error signal is applied to the VFOthrough a suitable loop filter 1314 to stably lock the phase.

A non-uniform transfer function 1306 may be applied to the offset crankangle to produce a desired plate angle. This may incorporate non-uniformrotation as shown in FIGS. 7BA and 7CA.

The strobe light may be used to illuminate the rotating valve plate andobserve the phase angle. Using this approach, the calibration offset canbe established.

Additional capabilities are possible. Examples include calibratingmotor(s) relative to a known position, and a communication protocol.

In the embodiment just described, the location of the moveable memberwithin the chamber is inferred from a signal received from a linkagethereto (e.g. a crankshaft). However, this is not required, and otherembodiments could involve valve actuation based upon a signal indicatingthe location of the moveable member within the chamber.

For example, in certain embodiments a member may rotate within a chamberin response to expanding gas. Examples of such structures include butare not limited to a screw, a turbine, a quasi-turbine, a vane, a lobe,a scroll, or a gerotor. In such cases, valve actuation could becoordinated by a PLL based upon the location of the rotating membersensed directly within the chamber, for example through optical ormagnetic principles.

Moreover, while embodiments described above employ PLL based upon asignal indicating rotation of a moveable member or linkage thereto, thisis also not required. Alternative embodiments could coordinate valveactuation with other types of motion via a PLL.

For example, A phase-locked loop can work with an intermittent referencesignal. When the signal is present, the loop could adjust the VCOcontrol up or down to match. When the reference signal is not present,the VCO control could remain at its current value. Thus if valveactuation is to be coordinated with a type of motion other than rotation(such as reciprocating motion), the position of the member or linkagethereto could be sensed intermittently in order to provide the basis forvalve actuation based upon a phase-locked loop.

For example, certain approaches could use a sensor to produce a pulsewhen a reciprocating moveable member such as a liquid or free piston isat or near TDC. This position of the moveable member could be detectedutilizing sensors in communication with the chamber, for example anopto-interrupter or hall effect sensor in the case of a free piston, oran ultrasonic sensor to detect a position of a liquid piston. While theresulting pulse would occur only once per expansion cycle, it would besufficient to phase lock the valve to the member that is moving inresponse to expanding gas, or being driven to compress gas within thechamber.

It is noted that the particular embodiment of FIGS. 13A-B utilizes ashaft encoder on the crankshaft, an arrangement which yields many pulsesper revolution. Such a configuration desirably makes the response timeof the resulting PLL lock much shorter.

1. A method comprising:

providing a gas flow valve to a chamber having a moveable member; and

coordinating actuation of a gas flow valve according to a position ofthe moveable member utilizing a phase lock loop (PLL).

2. A method as in claim 1 wherein the PLL is based upon a signalindicating the position.

3. A method as in claim 2 wherein the moveable member is configured torotate within the chamber.

4. A method as in claim 3 wherein the moveable member comprises a rotor.

5. A method as in claim 1 wherein the moveable member is configured totransmit power from the chamber via a linkage.

6. A method as in claim 5 wherein the PLL is based upon a signalindicating a position of the linkage.

7. A method as in claim 6 wherein the moveable member is configured toreciprocate within the chamber.

8. A method as in claim 7 wherein the linkage is configured to convertreciprocating motion to shaft torque.

9. A method as in claim 8 wherein the linkage comprises a mechanicallinkage.

10. A method as in claim 9 wherein the mechanical linkage comprises acrankshaft.

11. A method as in claim 5 wherein the linkage comprises a hydrauliclinkage.

12. A method as in claim 11 wherein the hydraulic linkage comprises apump/motor.

13. A method as in claim 11 wherein the PLL is based upon a signalindicating the position.

14. A method as in claim 1 wherein the gas flow valve is actuated byrotational motion.

15. A method as in claim 1 wherein the gas flow valve is actuated bylinear motion.

As described in detail above, certain valve embodiment are particularlysuited for implementation in conjunction with a host computer includinga processor and a computer-readable storage medium. Such a processor andcomputer-readable storage medium may be embedded, and/or may becontrolled or monitored through external input/output devices.

FIG. 15 is a simplified diagram of a computing device for processinginformation. This diagram is merely an example, which should not limitthe scope of the claims herein. One of ordinary skill in the art wouldrecognize many other variations, modifications, and alternatives.Embodiments can be implemented in a single application program such as abrowser, or can be implemented as multiple programs in a distributedcomputing environment, such as a workstation, personal computer or aremote terminal in a client server relationship.

FIG. 15 shows computer system 1510 including display device 1520,display screen 1530, cabinet 1540, keyboard 1550, and mouse 1570. Mouse1570 and keyboard 1550 are representative “user input devices.” Mouse1570 includes buttons 1580 for selection of buttons on a graphical userinterface device. Other examples of user input devices are a touchscreen, light pen, track ball, data glove, microphone, and so forth.FIG. 15 is representative of but one type of system for embodying thepresent invention. It will be readily apparent to one of ordinary skillin the art that many system types and configurations are suitable foruse in conjunction with the present invention. In an embodiment,computer system 1510 includes a Pentium™ class based computer, runningWindows™ XP™ or Windows 7™ operating system by Microsoft Corporation.However, the apparatus may use other operating systems/architectures.

As noted, mouse 1570 can have one or more buttons such as buttons 1580.Cabinet 1540 houses familiar computer components such as disk drives, aprocessor, storage device, etc. Storage devices include, but are notlimited to, disk drives, magnetic tape, solid-state memory, bubblememory, etc. Cabinet 1540 can include additional hardware such asinput/output (I/O) interface cards for connecting computer system 1510to external devices external storage, other computers or additionalperipherals, further described below.

FIG. 15A is an illustration of basic subsystems in computer system 1510of FIG. 15. This diagram is merely an illustration and should not limitthe scope of the claims herein. One of ordinary skill in the art willrecognize other variations, modifications, and alternatives. In certainembodiments, the subsystems are interconnected via a system bus 1575.Additional subsystems such as a printer 1574, keyboard 1578, fixed disk1579, monitor 1576, which is coupled to display adapter 1582, and othersare shown. Peripherals and input/output (I/O) devices, which couple toI/O controller 1571, can be connected to the computer system by anynumber of approaches known in the art, such as serial port 1577. Forexample, serial port 1577 can be used to connect the computer system toa modem 1581, which in turn connects to a wide area network such as theInternet, a mouse input device, or a scanner. The interconnection viasystem bus allows central processor 1573 to communicate with eachsubsystem and to control the execution of instructions from systemmemory 1572 or the fixed disk 1579, as well as the exchange ofinformation between subsystems. Other arrangements of subsystems andinterconnections are readily achievable by those of ordinary skill inthe art. System memory, and the fixed disk are examples of tangiblemedia for storage of computer programs, other types of tangible mediainclude floppy disks, removable hard disks, optical storage media suchas CD-ROMS and bar codes, and semiconductor memories such as flashmemory, read-only-memories (ROM), and battery backed memory.

According to particular embodiments, active valve control may be part ofa control loop based upon detected operating parameters of the system.Such a control loop may be implemented through a host computer as justdescribed. FIG. 14 shows a simplified view of an embodiment of a controlloop.

In particular, the active control loop 1400 comprises valving 1402 thatis controlled based upon input signal(s) 1403 received from controlsystem 1404 comprising a processor 1405 in communication with acomputer-readable storage medium 1407. Such a computer-readable storagemedium can be based upon magnetic, optical, semiconductor, or otherprinciples, as is well known in the art.

According to certain embodiments, such inputs from the control systemcould comprise voltages supplied to a motor such as a stepper motor,that is responsible for actuating the valve. In particular embodiments,the timing and/or magnitude of the input signal(s) may be determined bythe controller.

Performance of a gas compression (energy storage) or gas expansion(energy recovery) event, results in one or more system parameters 1406that can be sensed. Examples of such system parameters include but arenot limited, to temperature of the compressed or expanded gas exhaustedthrough the valving, pressure of the compressed or expanded gasexhausted through the valving, temperature of liquid separated fromexhaust through the valving, speed of a shaft transmitting power (suchas a crankshaft), and torque of a shaft transmitting power.

The sensed parameters are in turn communicated back to the controlsystem. Based upon these parameters and other factors, relevantinstructions stored in the form of computer code in the storage medium,may cause the processor to actively change the inputs to the valving.

For example, sensed parameters indicating a high pressure of gasexhausted through the valving after performance of gas expansion, mayindicate less efficient performance. Accordingly, the processor couldinstruct change in the valve timing to reduce a duration of openness ofthe valve responsible for intake of the compressed gas prior toexpansion. This will in turn reduce the quantity of gas available forexpansion within a fixed volume of a cylinder, and hence the finaloutput pressure differential, thereby improving efficiency.

In another example, sensed parameters indicating a high temperature ofgas exhausted through the valving after performance of gas compression,may also indicate less efficient performance. Accordingly, the processorcould instruct change in the valve timing to reduce a duration ofopenness of the valve responsible for intake of the gas prior tocompression. This will in turn reduce the quantity of gas available forcompression within a fixed volume of a cylinder, but improvethermodynamic efficiency of the compression process.

In still another example, sensed parameters indicating a high torque ofthe shaft communicating power from expanding gas, may also indicate lessefficient performance. Based upon this sensed data, the processor couldinstruct change in the valve timing to reduce a duration of openness ofthe valve responsible for intake of compressed gas for expansion. Thiswill in turn reduce the quantity of gas available for expansion andhence the power of the output, while improving efficiency.

As indicated previously, efficiency of operation of the system may bebalanced with an output of power (expansion), or of compressed gas(compression). Thus active valve control according to embodiments of thepresent invention is certainly not limited to the particular examplesgiven above, and alternatives could be utilized to favor output overefficiency.

Moreover, as discussed in detail below in connection with FIG. 9_,certain embodiments may provide other forms of desired output (such ascontrol over temperature). Accordingly, various embodiments could focusupon active valve control approaches to achieve those desired outputs,while balancing efficiency versus power.

Ideally efficient operation generally occurs when the valves are openedwith the pressure being equal across the valve. In a practical system,perturbing the opening and closing times around this ideal can improveefficiency.

Thus various control loops may be employed based upon sensed quantitiesincluding but not limited to, inlet pressure, in-chamber pressure, andoutlet pressure, in order to adjust these parameters. Additionally,efficiency may be estimated from such values as shaft RPM and torque,and air flow rate in conjunction with the pressures and temperaturesmentioned earlier.

In certain situations, a goal may be to maximize efficiency. However, inother situations other goals are possible, for example maximizing poweroutput, or matching a desired power output, or some desired combinationof these. The required output power could come from additionalcomputation that may consider factors as time of day, time of year,weather, electricity pricing models, and/or historical demand patternsof a particular user or consumer population.

The particular embodiments described so far are for purposes ofillustration only, and should not be taken as limiting. For example,while the above embodiments have featured one valve plate rotatingrelative to port(s) present in a fixed housing, this is not required andalternative embodiments could feature multiple valve plates rotatingrelative to one another.

And while the above embodiments feature valve elements moveable in arotational manner to effect opening and closure, this is also notrequired by the present invention. According to alternative embodiments,other forms of relative motion between valve elements could be used toeffect opening and closure.

One example of such alternative relative motion, is linear motion. Suchlinear motion could be achieved, for example, utilizing operation of acrank, gear, or other linkage attached to a shutter and moveable byoperation of a gear driven by a motor. In such an alternativeembodiment, appropriate seals and bearings could be employed to impartthe desired functional characteristics for the valve under differentpressure conditions.

In one specific embodiment, the valve may take the form of a sliding “D”valve, as has been previously used on steam engines. The sliding valveelement could be linked to an eccentric on the crankshaft to control theflow of steam into the cylinder. This is described generally in“Steam-Engine Design”, from the Lost Technology Series reprinted byLindsay Publications, (1983), which is incorporated by reference in itsentirety herein for all purposes. Also incorporated by reference hereinfor all purposes is “Modern Steam Engines” by Joshua Rose M. E, HenryCarey Baird & Co., Philadelphia, Pa. (1887) reprinted by Astragal Press(2003), which is incorporated by reference in its entirety herein.According to certain embodiments of the present invention, one slidingelement of such a D valve could be used to control steam flow, withanother sliding aperture used to control duration.

In embodiments of valves employing linear motion, the direction ofsliding of the elements need not be in the same or even oppositedirection relative to one another. In certain embodiments the elementscould be actuable in directions offset from one another by some angle,in order to achieve a desired valve area/timing profile.

While the embodiments shown and described above have featured circularvalve elements, this is also not required, and alternative embodimentscould utilize other valve shapes. For example, one alternativeembodiment could utilize gas flow through nested cylinders experiencingrelative rotation (or linear motion/sliding) to selectively overlap ofopening in the side, in a manner analogous to a sleeve valve.

While the rotating plate is described here are substantially planar,other shapes may be employed. Examples of such shapes are any surface ofrevolution including but not limited to, a portion of a sphere, aportion of a cone, a portion of a cylinder, a portion of a paraboloid,or a portion of a hyperboloid. The corresponding fixed surfaces could besimilarly shaped. While such a change in shape does not affect theoperation of the valve, it may have other beneficial effects, such asreduction of dead volume.

A valve according to various embodiments may function as an inlet valveand/or as an outlet valve to a gas expansion and/or compression chamber.Where the same chamber serves for both compression and expansion of gas,the valve may be configured to operate in a bi-directional manner.

In certain embodiments, the valve may be configured to allow the flow ofa gas-liquid mixture that has been created in an upstream mixingchamber. In such a configuration, embodiments of the valve designdesirably offer an unobstructed straight path to the flowing gas-liquidmixture. This discourages coalescence of entrained liquid droplets,allowing their passage to effect the desired heat exchange withcompressing/expanding gas within the chamber.

FIGS. 10A-10H show various views of one embodiment of a rotary gas flowvalve. FIG. 10A is an exploded view showing certain valve components,but omitting the top cover. FIG. 10B shows those elements of FIG. 10A inassembled form.

In particular, the rotary valve 10100 comprises a lower housing 10102defining ports 10104 a and 10104 b. Lower housing 10102 is fixed inplace, and does not rotate.

Lower housing 10102 further includes two raised edges 10106 proximate tothe respective ports. The function of these raised edge features isdiscussed below.

The size, shape, and orientation of the ports in the lower housing, isdesigned to match openings that are present in a rotatable valve plate.Specifically, the rotary valve 10100 also comprises valve plate 10110defining openings 10112 a and 10112 b corresponding in size and shapewith the ports 10104 a and 10104 b.

Valve plate 10110 is supported by bearing 10120, and is rotated bystepper motor 10122 via drive shaft 10124. Rotation of valve plate 10110relative to stationary lower housing 10102 to align openings 10112 a,10112 b with respective ports 10104 a, 10104 b, results in opening ofthe valve. Continued rotation of valve plate 10110 relative tostationary lower housing 10102 that does not align openings 10112 a,10112 b with respective ports 10104 a, 10104 b, results in closure ofthe valve.

FIG. 10C shows one particular embodiment of a valve unit as assembledand installed, including the inner cover 10140 and the upper housing10194. In particular, the valve unit fits into a side of a compressorand/or expander cylinder, where it seals at its lower end by a metal tometal seal at location 10130 and at its upper end by an O-ring atlocation 10132. Gases flow to/from the chamber through ports in thevalve, and to/from the external environment through passages 10134 inthe side of the valve.

Various elements of the valve may offer streamlined surfaces to flowinggas, thereby avoiding resistance leading to pressure losses. Forexample, FIG. 10D shows the rear surface 10103 of lower housing 10102facing the chamber, that is not visible in the view of FIG. 10A. FIG.10E shows inner cover 10140 offering a streamlined profile to thevalve's external side.

During operation, stepper motor 10122 receives a synchronizing signalfrom within the chamber. In one embodiment, this synchronizing signal isfrom a pulse generator driven off of a linkage (such as a crankshaft)that is in communication with the moveable element (such as a solidpiston) present within the gas expansion and/or compression cylinder.

The stepper motor 10122 may drive the valve at half compressor speed.Such a configuration allows the ports 10104 a, 10104 b and respectiveopenings 10112 a, 10112 b to comprise pairs of 45 degree wide openings,that are located 180 degrees apart. This desirably results in a balancedrotating mass for the valve plate.

Because the port width is 45 degrees and the aperture width is also 45degrees, the total duration from open to close of the valve is 90degrees. Since the valve is rotating at half compressor speed, the valveis open for 180 degrees of compressor rotation or one half a crankshaftrevolution.

The stepper motor 10122 may be fitted with an encoder and with anelectronic index marker. This allows accurate synchronization of thestepper motor with the compressor. The electronic index maker is alignedwith a known position of the valve opening such that it can beelectronically compared with the piston position.

The use of a stepper motor to control rotational movement of the valveplate, may offer several potential benefits. One such benefit is theability to shift the relationship of the valve to the compressor, at anytime. In particular, the stepper motor can be controlled to allow timingof the valve to be advanced or retarded.

Another possible benefit is the ability to vary the pulse rate drivingthe stepper motor. For example, varying the pulse rate of the steppermotor within one revolution may allow the valve to open more quicklyand/or to remain fully open for a longer time.

Specifically, a stepper motor allows the rotational speed to be changedwithin a single rotation. Thus the valve can be opened more quickly,allowed to stay fully open for a longer period, and then sped up toclose within the prescribed period.

Under certain circumstances, a high degree of control over the state ofopenness of the valve may need to be exercised. In order to provide suchan ability to further adjust the flow of gases through the valve, theembodiment of FIGS. 10A-H also includes a fixed aperture 10160 that isrotatably supported upon lower housing 10102 by bearing 10121.

The fixed aperture 10160 defines cutouts 10162 a, 10162 b whose size,location, and shape correspond with those of ports 10104 a, 10104 b andopenings 10112 a, 10112 b. The cutouts 10162 a, 10162 b are alsodesigned to accommodate the raised edges 10106 of the lower housing1002. In particular, these raised edges 1006 serve to block off gas flowfrom getting around the front edge of the fixed aperture so that as thetrailing edge is moved to shorten the duration of the valve opening, thegases are denied a “short-circuit” path at the front edge.

FIGS. 10F and 10G show the valve with the fixed aperture in differentpositions. In FIG. 10F the fixed aperture is rotated such that thealignment of the cutouts of the valve plate with the ports in thehousing, result in the valve being fully open. In this position thefront edge of the cut-out is aligned with the raised edge of the raisedfeature, thereby blocking any short-circuit gas flow path.

In FIG. 10G the fixed aperture is rotated such that the alignment of thecutouts of the valve plate with the ports in the housing, result in thevalve being only partially open. In this manner, rotation of the fixedaperture in either direction can be used to effectively control anamount of openness of the valve. In this position the front edge of thecut-out remains aligned with the raised edge of the raised feature inorder to prevent a short-circuit gas flow path.

The position of the fixed aperture is adjusted by a second stepper motor10156 which drives a pinion shaft 10158 through flexible couplings10161. The pinion in turn drives an internal gear segment 10159 that isattached to a raised perimeter 10160 a of the fixed aperture.

In particular, the outer diameter D of the fixed aperture is larger thanthe diameter D′ of the valve plate. The raised profile of the perimeter10160 a makes room for the gear segment 10159. FIG. 10H shows aperspective view of the underside of the inner cover 10140 showingrecess 10142 where the gear segment engages the pinion shaft.

In this particular embodiment, a substantial gear reduction allowed thesecond stepper motor driving the fixed aperture to be made smaller. Thisgear reduction also enhances accuracy of positioning of the fixedaperture.

The start position of the fixed aperture can be verified by a smallmagnet (not shown in FIG. 10H) attached to the gear segment (also notshown in FIG. 10H). This magnet is read by a Hall effect sensor 10176.

A seal may be present around the perimeter of the fixed aperture, inorder to help prevent the leakage of gases.

During operation, the different sides (chamber, external) of the valvewill typically experience substantially different pressures. Suchdifferential pressures acting on the exposed surface of the valve, cangive rise to friction.

Friction may be reduced in a number of ways. For example, the rotatingelement (valve plate and/or fixed aperture) can be made fairly thick andthus stiff in bending. Bearings having a low coefficient of friction(such as axial needle thrust bearings) can then be used to support therotating element near its center of rotation.

Since the friction is acting at the smallest possible radius, theresulting torque to be overcome may be kept minimal. The size of thestepper motors and power draws can thus be minimized.

In the particular embodiment shown, a first needle thrust bearing 10121is present between the fixed aperture and the lower housing, and asecond needle thrust bearing 10120 is present between the fixed apertureand the valve plate. Another needle thrust bearing is present betweenthe valve plate and the cover. Seals may retrain light grease on all thebearings.

The presence of pressure differentials across the valve may also createthe possibility of unwanted gas leakage. Such leakage can be inhibitedin a number of ways.

For example, leakage can be reduced by maintaining small clearancesbetween the valve components. Leakage can also be reduced by making leakpath distances as long as possible. The raised edges in the lowerhousing also serve to restrain leakage, as does a seal around the edgeof the fixed aperture.

Gas leakage can further be inhibited by using fixed seals 10170 mountedin dove-tailed grooves 10172 present on the underside of the inner cover10140, as shown in FIG. 10H. This positioning allowed the seals to sealagainst the rotating face of the valve plate, thereby blocking apossible escape path for leaking gases to the external environment.

One potential advantage offered by embodiments of valves, is the abilityto operate relative to a location of a piston within the chamber. Thisis in contrast with conventional compressor valve designs, that areconfigured to open or close based upon a pressure differential. Becausethe pressure differential experienced by a valve will change dependingupon whether the chamber is functioning in compression or expansion,valve embodiments according to the present invention can function in anapparatus suited to both.

Another potential advantage offered by valve embodiments, is the abilityto vary valve events relative to piston location. One example of a valveevent that can be varied relative to piston location, is the duration ofvalve opening.

An instance where the duration of valve opening may desirably bechanged, is early closure to admit for expansion an amount of gas thatis less than a full volume of the chamber, thereby controlling an amountof power output. Another instance of changing the duration of valveopening, is early closure to exhaust less than the full volume of gasexpanded in the chamber, thereby reducing a pressure differentialencountered by gas being inlet for the next expansion cycle.

Still another possible advantage offered by some embodiments, is areduction in pressure losses. This is achieved by having the gases flowalong straight paths through the port openings.

While the above embodiment relates to a valve design utilizing aseparate fixed aperture element, this is not required by the presentinvention. Certain embodiments could employ relative motion between justtwo pieces.

Moreover, while the above embodiment relates to a valve design having afirst plate rotatable relative to a stationary housing, this is also notrequired. An alternative embodiment of a valve design could comprise twoor more elements that are moveable relative to one another.

While the above embodiment features valve elements moveable in arotational manner by a stepper motor, this is not required by thepresent invention. According to alternative embodiments, motion could beimparted to valve elements by other than a stepper motor, for example byan air motor, a AC motor, or a DC motor (such as a brushless DC motor),in order to effect opening and closure of the valve.

According to alternative embodiments, the valve(s) could also beoperated by gears, belts, or chains off the crankshaft. Variable timingcould be accomplished by a hydraulic or pneumatic phase displaceablepulley or gear.

Certain valve embodiments according to the invention could employ vaneor scroll-type structures. Rotation of the vanes/scrolls relative to oneanother could be accomplished with pressurized oil or air, withreversion to the unactuated position accomplished through the use ofreturn springs.

Embodiments of valve structures according to the present invention,could be adapted to receive a flow of liquid for injection into theflowing gas. For example, FIG. 10I shows a perspective view of anembodiment of a valve having nozzles 10190 that are in fluidcommunication with a fluid source, through passages 10192 present in anupper housing 10194. In certain embodiments the nozzles could beconfigured for threadable engagement with the housing, in order tofacilitate removal, replacement, inspection, and/or maintenance.

1. A valve comprising:

a first plate defining a first opening in a first plane;

a second plate defining a second opening in a second plane parallel tothe first plane, the second plate moveable relative to the first plateto align the second opening with the first opening; and

a bearing between the first plate and the second plate.

2. A valve according to claim 1 wherein the second plate is rotatablerelative to the first plate.

3. A valve according to claim 2 wherein the bearing comprises a thrustbearing.

4. A valve according to claim 2 further comprising:

a third opening in the second plate and in the second plane, the thirdopening symmetric to the second opening to balance a mass of the secondplate; and

a fourth opening in the first plate and in the first plane, the fourthopening aligned with the third opening when the second opening isaligned with the first opening.

5. A valve according to claim 2 further comprising:

a stepper motor; and

a drive shaft in communication with the stepper motor and with thesecond plate.

6. A valve according to claim 2 wherein:

the valve is in fluid communication with a cylinder having a pistondisposed therein; and

rotation of the second plate is synchronized with movement of thepiston.

7. A valve according to claim 6 wherein rotation of the second plate issynchronized based upon a synchronizing signal from a pulse generatordriven off of a linkage in communication with the piston.

8. A valve according to claim 7 wherein the linkage comprises acrankshaft.

9. A valve according to claim 6 further comprising:

a stepper motor; and

a drive shaft in communication with the stepper motor to rotate thesecond plate.

10. A valve according to claim 9 wherein the stepper motor is fittedwith an encoder and/or an electronic index marker for synchronizationwith the piston.

11. A valve according to claim 2 further comprising a nozzle in fluidcommunication with a liquid source.

12. A valve according to claim 2 further comprising:

a third plate defining a third opening in a third plane, the third platepositioned between the first plate and the second plate, the third platemoveable relative to the first plate to align the third opening with thefirst and second openings; and

a second bearing between the first plate and the third plate, whereinthe bearing is between the third plate and the second plate.

13. A valve according to claim 12 further comprising a gear segment incommunication with a motor to rotate the third plate.

14. A method comprising:

providing a first plate defining a first opening in a first plane;

providing a second plate defining a second opening in a second plane;

supporting the first plate on a bearing; and

moving the first plate relative to the second plate to align the firstopening with the second opening and allow gas to flow therethrough.

15. A method according to claim 14 wherein the first plate is rotatedrelative to the second plate to align the first opening with the secondopening.

16. A method according to claim 15 wherein the first plate is supportedon a thrust bearing.

17. A method according to claim 15 wherein the first plate is rotated ina first direction to align the first opening with the second opening,and then continued to be rotated in the first direction to preventalignment of the first opening with the second opening.

18. A method according to claim 15 wherein the first plate is rotated bya stepper motor.

19. A method according to claim 18 wherein a timing of pulses of thestepper motor are varied.

20. A method according to claim 15 further comprising:

providing a third plate defining a third opening in a third plane;

supporting the third plate on a second thrust bearing; and

rotating the third plate relative to the second plate to control aquantity of gas flowed through the second opening.

21. A method according to claim 20 wherein the third plate is rotated bya gear

1. An apparatus comprising:

a member disposed within a chamber and moveable in response to gasexpansion;

a physical linkage in communication with the member;

a valve selectively actuable to permit a compressed gas to enter thechamber, the valve comprising,

-   -   a first plate defining a first opening,    -   a second plate defining a second opening and moveable relative        to the first plate to align the second opening with the first        opening, and    -   a bearing between the first plate and the second plate;

a nozzle configured to spray liquid droplets; and

a gas-liquid separator configured to separate liquid from expanded gasreceived from the chamber.

2. An apparatus according to claim 1 wherein the nozzle is configured toimpart a rotational motion to liquid flowing therethrough.

3. An apparatus according to claim 1 wherein the nozzle is positionedwithin the chamber.

4. An apparatus according to claim 1 wherein the nozzle is positionedwithin the valve.

5. An apparatus according to claim 1 further comprising a gas-liquidmixing chamber positioned upstream of the valve.

6. An apparatus according to claim 5 wherein the nozzle is positioned inthe gas-liquid mixing chamber.

7. An apparatus according to claim 1 wherein the second plate isrotatable relative to the first plate.

8. An apparatus according to claim 1 wherein the bearing comprises athrust bearing.

9. An apparatus according to claim 1 further comprising a stepper motorin communication with the second plate.

10. An apparatus according to claim 9 wherein the chamber is inselective fluid communication with the gas-liquid separator through asecond valve comprising:

a third plate defining a third opening,

a fourth plate defining a fourth opening and moveable relative to thethird plate to align the fourth opening with the third opening, and

a second bearing between the third plate and the fourth plate.

11. An apparatus according to claim 10 further comprising a secondstepper motor in communication with the fourth plate.

12. An apparatus according to claim 1 wherein the member comprises areciprocating piston.

13. An apparatus according to claim 12 wherein the physical linkage isconfigured to convert reciprocating motion of the piston into shafttorque.

14. An apparatus according to claim 13 wherein the physical linkagecomprises a mechanical linkage.

15. An apparatus according to claim 14 wherein the mechanical linkagecomprises a crankshaft.

16. An apparatus according to claim 11 wherein the physical linkagecomprises a pneumatic/hydraulic linkage.

17. An apparatus according to claim 16 wherein the pneumatic/hydrauliclinkage comprises a pneumatic/hydraulic motor.

18. An apparatus according to claim 1 further comprising an electricalgenerator in communication with the physical linkage.

19. An apparatus according to claim 1 further comprising:

a second member disposed within a second chamber and moveable by thephysical linkage to compress gas therein;

a second valve selectively actuable to permit a gas to enter the secondchamber, the second valve comprising,

a third plate defining a third opening,

a fourth plate defining a fourth opening and moveable relative to thethird plate to align the fourth opening with the third opening, and

a second bearing between the third plate and the fourth plate; and

a second gas-liquid separator configured to separate liquid fromcompressed gas received from the second chamber.

20. An apparatus according to claim 19 wherein the second membercomprises a reciprocating piston, and the physical linkage comprises acrankshaft

The fixed aperture feature disclosed in the embodiment of FIG. 10Aprovides variable valve area, rather than variable valve duration. Incertain applications, however, it may be desirable to utilize a valvedesign exhibiting variable duration as well as variable valve area.

Accordingly, FIGS. 12A-I show various views of an alternative embodimentof a valve design which retains the variable valve area functionality,and also provides for variable valve duration. Operation of a similarvalve has been discussed previously in connection with FIGS. 5A-C.

In particular, FIG. 12A shows an exploded view of an alternativeembodiment of a valve structure 1200 according to the present invention,which includes a fixed housing 1201 defining ports therein, and a valveplate 1202 and a fixed aperture 1203 that are each rotatable relative tothe fixed housing and independent of one another. FIG. 12B shows across-sectional view of the fully assembled valve.

In order to provide true variable valve opening duration, the embodimentof FIGS. 12A-I features a moving aperture 1209 that functions to changethe width of the opening in the valve plate 1202. Since the plate 1202is being constantly rotated by the stepper motor 1204, a controllablemechanism was designed to impart a linear motion along the axis of thevalve drive shaft 1206, that could be converted into rotational motionin order to control the width of the valve opening.

This rotational motion was then used to move the moving aperture 1209relative to the valve plate 1202 in an accurately controlled manner.This allowed the effective width of the valve opening to be varied overa range of approximately 45 degrees.

In the embodiment of FIGS. 12A-I, a multi-start high lead screw 1208(shown enlarged in FIG. 12I) is used to convert linear motion intorotational motion. Such a multi-start high lead screw has a very highlead angle in the threads, and therefore it is possible to back-drivethe screw by pushing on a nut 1210 (shown enlarged in FIG. 12G) incontact therewith.

In the particular embodiment of FIGS. 12A-I, the screw was affixed tothe valve drive shaft via a pin 1212. The nut was slideably affixed to amoving aperture 1209 via a hollow shaft 1214 coincident with the driveshaft of the valve plate 1202.

When a linear actuator 1216 used to drive the mechanism is in theretracted position, a spring 1218 having one end supported by a controlflange 1230 and the other end acting on the nut, forces the valve toreturn to the fully open position.

The motion from the linear actuator is imparted onto the sliding nut byuse of a lever arm 1220, that both reduces the force required by theactuator and amplifies the motion of the nut so that the actuatorpositions the nut more accurately. The lever arm acts on a rotatingcollar 1222 that is isolated from the rotation of the valve by ananti-friction thrust bearing 1224, such that only linear motion isimparted into the nut.

When the linear actuator is extended, the nut is pushed down within ahexagonal guide 1226 (shown enlarged in FIG. 12H), thereby causing thehollow shaft 1214 with the moving aperture 1209 (including projectingportion 1209 a), to rotate relative to the valve plate that is attachedto the drive shaft. The motion of the hollow shaft and half-valve plateis counter-clockwise due to the left hand thread. This motion alsocompresses the return spring 1218.

While the embodiment of FIG. 12 shows the fixed aperture as beingpositioned proximate to the chamber side, this is not required.Alternative embodiments could position the fixed aperture distal fromthe chamber side, thereby potentially reducing an amount of dead volumeattributable to valve structure.

And while the embodiment of FIG. 12 shows the moving aperture as beingpositioned distal to the chamber side, this is not required. Alternativeembodiments could position the moving aperture on the other side of theplate valve, proximate to the chamber side.

While the above valve embodiments have been described in connection withinlet of compressed gas or gas-liquid mixtures to an expansion cylinder,other uses are certainly possible. For example, in certain applications,a valve according to an embodiment of the present invention could beutilized to flow gas from an expansion, compression, orexpansion/compression chamber.

Embodiments of the present invention could also include a compressionrelease structure. As described below, such a compression release couldallow the crankshaft of the machine to be rotated at low speed withminimum force and pressure loading. Such low speed rotation may bebeneficial for one or more prospective uses.

For example, one use for such low speed rotation is to displace anyfluids trapped in the cylinder that may have accumulated after extendedperiods of non-operation. Another use for such low speed rotation is toallow the machine to be slowly rotated so that rotary valves driven bystepper motors can be synchronized with the crankshaft position of themachine. Still another use would be as a safety device, where thecompression release valve is operated if certain operating limits havebeen exceeded.

As described above, rotary valves may allow the same apparatus to beused as a compressor and as an expander (an air motor) in order to drivea generator. In certain embodiments the rotary valves may be driven bystepper motors synchronized with the crankshaft utilizing electronicposition indicators.

To achieve synchronization the crank of the compressor may first berotated slowly. This allows the system to locate the electronic markeron the crankshaft, and adjust the positioning of the stepper motors sothat their electronic markers are in the correct relationship.

During this initial operation the timing of the valves relative to thepiston may not be correct, and could result in high pressure loads. Toavoid this condition, the compression release valves could be openedprior to rotating the crank. Then, once the rotary valves have beenproperly synchronized with the electronic indicia, compression releasevalves would be closed.

As shown in FIGS. 11A-D, some embodiments of the compression release11100 may be located within a head 11106 (shown transparent in FIG. 11Afor illustration) of a cylinder containing a double-acting piston 11102connected to a piston rod 11104. The views presented are simplified forillustration, and thus the piston may in fact be hollow rather thansolid.

The compression release may be present in the cylinder head togetherwith liquid spray nozzle(s) 11108. Although not shown in FIG. 11A, theopposite head 11107 of the cylinder could also include a correspondingcompression release and liquid spray nozzle(s).

In certain embodiments the compression release is in the form of apoppet type valve comprising a body 11114 with exhaust ports 11116, avalve 11118, return spring 11120, spring retainer 11122, cover 11124,multi-lead screw 11126, multi-lead nut 11127, torque arm 11128,stationary arm 11130, and cable adjuster 11132. In certain embodimentsthe valve may be unitized so that it can be preassembled prior toinstallation in the compressor.

The valve is normally held closed by the spring, which is sized toprovide a closing force is greater than the suction force of air thatmight act on the area of the face of the valve. Therefore, the valvewill only actuate is when pushed open by the multi-lead screw convertingthe torque supplied by a control cable acting on the torque arm, intoaxial force.

The multi-lead screw provides the mechanical advantage of a ramp, butalso has a high lead such that it lifts the valve at a rate of one-halfinch per turn. Since the lever moves about one-quarter turn, this liftsthe valve open one-eighth of an inch.

The cable can be operated by a linear actuator or comparable device.According to certain embodiments a linear actuator could be fitted toact directly on the valve, thereby eliminating the cable.

When the valve is opened the cylinder is in direct communication withthe atmospheric pressure, so it can neither build pressure nor pull avacuum. Gases are exhausted to just outside the cylinder head wheredrain lines communicate with the outside atmosphere. The exhaust portscould also connect to pipes connected to a vent tank where any watercould be reclaimed.

When the compressor first starts to rotate water in the cylinder wouldbe pushed out through the compression release valve, which is locatednear the bottom of the cylinder. The compression release valve couldalso be opened while the compressor is running in order to preventdamage (for example where sensors detect malfunctioning valves). Thiswould help prevent adverse high pressure conditions that might result.

Embodiments of gas storage units according to the present invention maybe suited to work in conjunction with compressed gas energy systems.Various such energy recovery systems are described in the '683application.

FIG. 8 shows a simplified view of one embodiment of such a compressedgas energy system. In particular, the system 800 includes acompressor/expander 802 comprising a cylinder 804 having piston 806moveably disposed therein. The head 806 a of the piston is incommunication with a motor/generator 808 through a piston rod 806 b anda linkage 810 (here a crankshaft).

In a compression mode of operation, the piston may be driven by themotor/generator 805 acting as a motor to compress gas within thecylinder. The compressed gas may be flowed to a gas storage tank 870, ormay be flowed to a successive higher-pressure stage for additionalcompression.

In an expansion mode of operation, the piston may be moved by expandinggas within the cylinder to drive the motor/generator acting as agenerator. The expanded gas may be flowed out of the system, or flowedto a successive lower-pressure stage for additional expansion.

The cylinder is in selective fluid communication with a high pressureside or a low pressure side through valving 812. In this particularembodiment, the valving is depicted as a single multi-way valve.However, the present invention is not limited to such a configuration,and alternatives are possible.

For example, in lieu of a single, multi-way valve, some embodiments ofthe present invention may include the arrangement of multiple one-way,two-way, or three-way valves in series. Examples of valve types whichcould be suitable for use in accordance with embodiments of the presentinvention include, but are not limited to, spool valves, gate valves,cylindrical valves, needle valves, pilot valves, rotary valves, poppetvalves (including cam operated poppet valves), hydraulically actuatedvalves, pneumatically actuated valves, and electrically actuated valves(including voice-coil actuated valves).

When operating in the compression mode, gas from the low pressure sideis first flowed into the cylinder, where it is compressed by action ofthe piston. The compressed gas is then flowed out of the cylinder to thehigh pressure side.

When operating in the expansion mode, gas from the high pressure side isflowed into the cylinder, where its expansion drives the piston. Theexpanded gas is subsequently exhausted from the cylinder to the lowpressure side.

Embodiments of the present invention utilize heat exchange betweenliquid and gas that is undergoing compression or expansion, in order toachieve certain thermodynamic efficiencies. Accordingly, the systemfurther includes a liquid flow network 820 that includes pump 834 andvalves 836 and 842.

The liquid flow network is configured to inject liquid into the cylinderto perform heat exchange with expanding or compressing gas. In thisembodiment, the liquid is introduced through nozzles 822. In otherembodiments, a bubbler may be used, with the gas introduced as bubblesthrough the liquid.

The liquid that has been injected into the cylinder to exchange heatwith compressed gas or expanding gas, is later recovered by gas-liquidseparators 824 and 826 located on the low- and high-pressure sidesrespectively. Examples of gas-liquid separator designs include verticaltype, horizontal type, and spherical type. Examples of types of suchgas-liquid separators include, but are not limited to, cycloneseparators, centrifugal separators, gravity separators, and demisterseparators (utilizing a mesh type coalescer, a vane pack, or anotherstructure).

Liquid that has been separated may be stored in a liquid collectorsection (824 a and 826 a respectively). A liquid collector section of aseparator may include elements such as inlet diverters includingdiverter baffles, tangential baffles, centrifugal, elbows, wavebreakers, vortex breakers, defoaming plates, stilling wells, and mistextractors.

The collected separated liquid is then thermally conditioned forre-injection. This thermal conditioning may take place utilizing athermal network. Examples of components of such a thermal networkinclude but are not limited to liquid flow conduits, gas flow conduits,heat pipes, insulated vessels, heat exchangers (including counterflowheat exchangers), loop heat pipes, thermosiphons, heat sources, and heatsinks.

For example, in an operational mode involving gas compression, theheated liquid collected from gas-liquid separator 826 is flowed throughheat exchanger 828 that is in thermal communication with heat sink 832.The heat sink may take one of many forms, including an artificial heatsink in the form of a cooling tower, fan, chiller, or HVAC system, ornatural heat sinks in the form of the environment (particularly at highlatitudes or altitudes) or depth temperature gradients extant in anatural body of water.

In an operational mode involving gas expansion, the cooled liquidcollected from gas-liquid separator 824 is flowed through heat exchanger852 that is in thermal communication with heat source 830. Again, theheat source may be artificial, in the form of heat generated byindustrial processes (including combustion) or other man-made activity(for example as generated by server farms). Alternatively, the heatsource may be natural, for example geothermal or solar in nature(including as harnessed by thermal solar systems).

Flows of liquids and/or gases through the system may occur utilizingfluidic and/or pneumatic networks. Examples of elements of fluidicnetworks include but are not limited to tanks or reservoirs, liquid flowconduits, gas flow conduits, pumps, vents, liquid flow valves, gas flowvalves, switches, liquid sprayers, gas spargers, mixers, accumulators,and separators (including gas-liquid separators and liquid-liquidseparators), and condensers. Examples of elements of pneumatic networksinclude but are not limited to pistons, accumulators, gas chambersliquid chambers, gas conduits, liquid conduits, hydraulic motors,hydraulic transformers, and pneumatic motors.

As shown in FIG. 8, the various components of the system are inelectronic communication with a central processor 850 that is incommunication with non-transitory computer-readable storage medium 854,for example relying upon optical, magnetic, or semiconductingprinciples. The processor is configured to coordinate operation of thesystem elements based upon instructions stored as code within medium854.

The system also includes a plurality of sensors 860 configured to detectvarious properties within the system, including but not limited topressure, temperature, volume, humidity, and valve state. Coordinatedoperation of the system elements by the processor may be based at leastin part upon data gathered from these sensors.

The particular system shown in FIG. 8 represents only one embodiment ofthe present invention, and alternative embodiments having other featuresare possible. For example, while FIG. 8 shows an embodiment withcompression and expansion occurring in the same cylinder, with themoveable element in communication through a linkage with amotor/generator, this is not required.

FIG. 9 shows an alternative embodiment utilizing two cylinders, which incertain modes of operation may be separately dedicated for compressionand expansion. Embodiments employing such separate cylinders forexpansion and compression may, or may not, employ utilize a commonlinkage (here a mechanical linkage in the form of a crankshaft) with amotor, generator, or motor/generator.

For example, FIG. 9A is a table showing four different basicconfigurations of the apparatus of FIG. 9. The table of FIG. 9A furtherindicates the interaction between system elements and various thermalnodes 14625, 14528, 14530, 14532, 14534, 14536, and 14540, in thedifferent configurations. Such thermal nodes can comprise one or moreexternal heat sources, or one or more external heat sinks, as indicatedmore fully in that table. Examples of such possible such external heatsources include but are not limited to, thermal solar configurations,geothermal phenomena, and proximate heat-emitting industrial processes.Examples of such possible such external heat sinks include but are notlimited to, the environment (particularly at high altitudes and/orlatitudes), and geothermal phenomena (such as snow or water depththermal gradients).

FIGS. 9BA-9BD are simplified views showing the various basic operationalmodes listed in FIG. 9A. The four different basic modes of operationshown in FIG. 9A may be intermittently switched, and/or combined toachieve desired results. FIGS. 9BE-BF show operational modes comprisingcombinations of the basic operational modes.

One possible benefit offered by the embodiment of FIG. 9 is the abilityto provide cooling or heating on demand. Specifically, the change intemperature experienced by an expanding or compressed gas, or aninjected liquid exchanging heat with such an expanding or compressedgas, can be used for temperature control purposes. For example, gas orliquid cooled by expansion could be utilized in an HVAC system.Conversely, the increase in temperature experienced by a compressed gas,or a liquid exchanging heat with a compressed gas, can be used forheating.

By providing separate, dedicated cylinders for gas compression orexpansion, embodiments according to FIG. 9 may provide such temperaturecontrol on-demand, without reliance upon a previously stored supply ofcompressed gas. In particular, the embodiment of FIG. 9 allows coolingbased upon immediate expansion of gas compressed by the dedicatedcompressor.

While FIGS. 8-9 show embodiments involving the movement of a solid,single-acting piston, this is not required. Alternative embodimentscould utilize other forms of moveable elements. Examples of suchmoveable elements include but are not limited to double-acting solidpistons, liquid pistons, flexible diaphragms, screws, turbines,quasi-turbines, multi-lobe blowers, gerotors, vane compressors, scrollcompressors, and centrifugal/axial compressors.

Moreover, embodiments may communicate with a motor, generator, ormotor/generator, through other than mechanical linkages. Examples ofalternative linkages which may be used include but are not limited to,hydraulic/pneumatic linkages, magnetic linkages, electric linkages, andelectro-magnetic linkages.

While the particular embodiments of FIGS. 8-9 show a solid piston incommunication with a motor generator through a mechanical linkage in theform of a crankshaft, this is not required. Alternative embodimentscould utilize other forms of mechanical linkages, including but notlimited to gears such as multi-node gearing systems (including planetarygear systems). Examples of mechanical linkages which may be used includeshafts such as crankshafts, gears, chains, belts, driver-followerlinkages, pivot linkages, Peaucellier-Lipkin linkages, Sarrus linkages,Scott Russel linkages, Chebyshev linkages, Hoekins linkages, swashplateor wobble plate linkages, bent axis linkages, Watts linkages, trackfollower linkages, and cam linkages. Cam linkages may employ cams ofdifferent shapes, including but not limited to sinusoidal and othershapes. Various types of mechanical linkages are described in Jones in“Ingenious Mechanisms for Designers and Inventors, Vols. I and II”, TheIndustrial Press (New York 1935), which is incorporated by reference inits entirety herein for all purposes.

Stubborn Poppet Valve

Embodiments relate to fluid flow valves comprising a member (such as apoppet or plate) moveable relative to a stationary seat, where the stateof the member may be maintained against countervailing forces withrelatively small expenditure of energy. According to one embodiment, apoppet displaced from seating in the valve seat, may be held in positionagainst opposing forces tending to close the valve, until a desired flowof gas through the valve has taken place. The poppet may then bereleased as desired, such that those opposing forces serve to passivelyclose the valve. The moveable member may be secured in position againstthe countervailing forces utilizing mechanical, magnetic,electromagnetic, or hydraulic mechanisms. Such valve embodiments may beparticularly suited to controlling flows of gases for compression and/orexpansion as an energy storage medium.

FIGS. 16A-D are simplified views showing operation of a valve embodimentduring a compression cycle in a structure comprising a reciprocatingpiston housed within a cylinder. These figures show that in compression,the valve embodiment functions entirely passively as a conventionalcheck valve.

Specifically, FIG. 16A shows that during a gas intake step where thepiston 1600 is moving toward the Bottom Dead Center (BDC) position, thecylinder 1602 may intake gas through the valve 1604 in communicationwith the low pressure side 1606. In FIG. 1A the pressure differentialbetween the chamber 1608 and the low pressure side, dispose the poppet1610 away from its valve seat 1612 such that the valve 1604 is in theopen state. By contrast, the pressure differential between the highpressure side 1614 and the chamber 1608, dispose the poppet 1616 intoits valve seat 1618, such that the valve 1620 is in the closed state.

FIG. 16B shows that at the point of the valve reaching BDC, the valvestates are passively maintained in their present valve states by theexisting pressure differentials between the chamber and the high- andlow-pressure sides.

FIG. 16C shows that upon the piston reversing direction and beginning tomove toward TDC, the pressure within the chamber rises. Upon thepressure differential between the chamber and the low pressure sideexceeding a predetermined cracking pressure (V_(crack-low)) of the lowpressure side valve 1604, that valve is passively closed.

FIG. 16D shows that as the piston continues to move upward with bothvalves closed, pressure within the cylinder builds until it exceeds acracking pressure (V_(crack-low)) of the high pressure side valve 1620.At this point, the poppet 1616 is displaced upwardly away from its valveseat 1618 by the pressure differential between the chamber and the highpressure side, thereby passively opening the valve 1620. Compressed gasis then exhausted to the high pressure side, where it may be stored,further compressed, or expanded to perform useful work, depending uponthe particular application.

The compression cycle is then repeated as the piston reaches TDC andreverses direction to intake additional gas for compression, as shown inFIG. 1A.

In summary, the valves in the compression cycle shown in FIGS. 16A-D actentirely passively, with their actuation attributable solely to thepressure differentials arising between the chamber and the low- andhigh-pressure sides. This is desirable insofar as no outside energyother than that responsible for driving the piston, is consumed.

FIGS. 17A-17E now show operation of the valve embodiment of FIGS. 16A-Dduring a corresponding expansion cycle. These figures show that inexpansion, the valve embodiment continues to function in a nearlypassive manner. In particular, only a force that holds and maintains apoppet in its existing state against opposing forces, is needed. At nopoint during the expansion cycle shown below, is energy required to beconsumed to actively open a valve against countervailing forces.

FIG. 17A shows the exhaust of gas which has been expanded during aprevious (downward) stroke of the piston. In this step, the naturalpressure differential extant between the high pressure side 1614 and thechamber 1608 does not exceed V_(crack-high), such that the poppet 116 isbiased downward into its corresponding seat 1618, and valve 1620 is inthe closed state.

Also in FIG. 17A, the poppet 1610 of the valve 1604 is maintained (held)in a position away from the valve seat 1612. Poppet 1610 had previouslyassumed this open position, due to a naturally-arising pressuredifferential between the chamber and the low pressure side exceedingV_(crack-low) during a previous expansion step (see discussion of FIG.17E below). Maintenance of the valve 1604 in this open state allows theexpanded gas to be exhausted from the cylinder.

FIG. 17B shows that at some later point as the piston continues to moveupward, the poppet 1610 is released from its held position. As thepressure differential extant between the chamber and the low pressureside does not exceed V_(crack-low), the poppet 1610 becomes seated inthe valve seat 1612 and the valve 1604 is passively closed.

Because the pressure differential between the chamber and the highpressure side has not yet exceeded V_(crack-high), the valve 1620remains sealed and pressure builds within the cylinder as the pistoncontinues to move upward.

FIG. 17C shows that as the piston approaches and reaches the TDCposition, the pressure builds within the chamber such that the pressuredifferential eventually exceeds V_(crack-high), causing poppet 1616 tomove away from the valve seat and valve 1620 to open. This in turnallows gas from the high pressure side to flow into the chamber forexpansion. In FIG. 17C, the displaced poppet 1616 is maintained inposition away from the valve seat, for example utilizing a mechanical orhydraulic mechanism as is discussed further below.

FIG. 17D shows the piston continuing to move downward toward BDC as moregas from the high pressure side enters through valve 1620 (beingmaintained in the open position) and expands within the chamber. Becausethe pressure within the chamber has not exceeded the cracking pressureof the low pressure side valve 1604, it remains closed.

FIG. 17E shows the piston approaching and reaching BDC. The poppet 1616is released, and the naturally-arising pressure differential between thehigh pressure side and the low pressure within the chamber closes thevalve 1620.

Moreover the drop in pressure due to expansion of gas within thecylinder, causes the pressure differential between the chamber and thelow pressure side to exceed V_(crack-low). Accordingly the low pressureside valve 1604 is passively opened and then held in the open position.This allows the chamber to be poised for the exhaust stage previouslydescribed in connection with FIG. 17A.

FIG. 17F plots piston position versus crank angle during the expansioncycle shown in FIGS. 17A-E. FIG. 17G plots pressure versus volume forthe expansion cycle of FIGS. 17A-E. In both FIGS. 17F and 17G, theintake valve corresponds to the valve allowing selective fluidiccommunication between the chamber and the high pressure side. Thedischarge valve corresponds to the low pressure side valve.

To summarize: the expansion cycle of FIGS. 17A-E utilizes thenaturally-occurring pressure differentials in order to achieve valveactuation. Specifically, releasing the moveable member from its heldstate closes the discharge valve on the low pressure side prior to thepiston reaching full TDC. This creates a residual pressure within thechamber that can be leveraged to passively actuate the intake valve onthe high pressure side.

Moreover, during the expansion cycle of FIGS. 17A-E, the valves actnearly passively. The only additional energy consumed, is that which isused to maintain them in a state already achieved by passive actuation.As disclosed below, this additional energy can be relatively small, andneed not be applied continuously.

Specifically, the force to maintain a valve in its previously-actuatedstate, may take one of several forms. For example FIGS. 18A-C showsimplified schematic views of a valve embodiment which relies upon amechanism operating based on mechanical principles to maintain valvestate against countervailing forces. In FIG. 18A the valve 1800 ispassively actuated to achieve an open state, with the pin 1802 withdrawnfrom the corresponding opening 1804 in the shaft of the valve poppet. InFIG. 18B, the valve 1800 is secured in the open state by causing pin1802 to enter and remain within the opening 1804 (for example utilizinga solenoid). In FIG. 18C removal of the pin from the opening, allows thevalve 1800 to be passively closed by the countervailing force.

FIGS. 19A-C show a simplified schematic view of an alternativeembodiment of a valve, which relies upon a mechanism operating based onhydraulic principles to maintain valve state against countervailingforces. In FIG. 19A the valve 1900 is passively actuated to achieve anopen state, with the secondary valve 1902 open to allow flow ofdisplaced fluid. In FIG. 19B, the valve 1900 is secured in the openstate by closing secondary valve 1902, thereby preventing fluid flow. InFIG. 19C, opening of the secondary valve 1902 permits fluid flow andreleases the poppet, allowing the valve 1900 to be closed passively bythe countervailing force.

Neither of the embodiments of FIGS. 18A-C or 19A-C require thecontinuous application of force in order to hold the valves in theiropen state. Instead, the force is applied momentarily to either to holdor release the valve. This reduces energy consumed by valve actuation.

Valve operation may be controlled based upon signals received from acentral processor in communication with a computer-readable storagemedium. Executable code present in such a storage medium may instructthe processor to control a timing of valve closure and/or opening, forexample by determining a time of release of a held moveable member suchas a poppet/plate.

While the above embodiments have described the use of mechanismsoperating based upon mechanical or hydraulic principles to hold thevalve in a previously-attained state, this is not required. Alternativeembodiments could employ mechanisms operating according to otherprinciples, including but not limited to magnetic, electrostatic, orpneumatic principles.

And while the above embodiments have described valves in which themoveable portion is capable of being held in the open state, this isalso not required. Alternative valve embodiments could be configured tobe held in the closed state against countervailing forces that wouldotherwise cause the valve to be open.

Moreover, while the above example has related to valves having a poppetmoveable relative to a valve seat, this is also not required.Alternative embodiments could employ other structures, such as amoveable plate. Still other types of moveable elements for valvesinclude but are not limited to sleeves, needles, and balls.

Furthermore, while the above embodiments have described valves for usewith a reversible compressor/expander comprising a solid pistonreciprocating within a cylinder, this is also not required. Embodimentsof valves could be employed with other types of structures, includingbut not limited to those employing rotating members enclosed withinwalls, for example screws, turbines, quasi-turbines, gerotors, vanecompressors/expanders, scroll compressors/expanders, and liquid ringcompressors/expanders.

1. An apparatus comprising:

a valve comprising a member moveable between a first state to engage aseat and block a flow of fluid therethrough, and a second state todisengage from the seat and allow the flow of fluid; and

a mechanism selectively configurable to maintain the state of the memberagainst a countervailing force exceeding a valve actuation force.

2. An apparatus as in claim 1 wherein the mechanism is configured tomaintain the member in the second state.

3. An apparatus as in claim 1 wherein the mechanism is configured tomaintain the member in the first state.

4. An apparatus as in claim 1 wherein the actuation force comprises apressure differential.

5. An apparatus as in claim 4 wherein the fluid flow comprises a gasflow.

6. An apparatus as in claim 1 wherein the member comprises a poppet.

7. An apparatus as in claim 1 wherein the member comprises a plate.

8. An apparatus as in claim 1 wherein the mechanism operates accordingto mechanical principles.

9. An apparatus as in claim 1 wherein the mechanism operates accordingto hydraulic or pneumatic principles.

10. An apparatus as in claim 1 wherein the mechanism operates accordingto magnetic principles.

11. An apparatus as in claim 1 wherein the seat is positioned between acompressed gas storage unit and a chamber.

12. An apparatus as in claim 11 wherein the chamber is defined by apiston within a cylinder.

13. An apparatus as in claim 11 wherein the chamber is defined by arotating element enclosed within walls.

14. An apparatus as in claim 11 further comprising:

a second valve comprising a second member moveable between a first stateto engage a second seat and block a flow of fluid therethrough, and asecond state to disengage from the second seat and allow the flow offluid; and

a second mechanism selectively configurable to maintain the state of thesecond member against a second countervailing force exceeding a secondvalve actuation force, wherein the second seat is positioned between thechamber and a low pressure side.

15. An apparatus as in claim 14 wherein the second mechanism isconfigured to maintain the second member in the second state.

16. An apparatus as in claim 14 wherein the second mechanism isconfigured to maintain the second member in the first state.

17. A method comprising:

providing a chamber in selective fluid communication with a compressedgas storage unit through an intake valve comprising a member selectivelymoveable to disengage from a seat;creating a residual pressure within the chamber to passively actuate themember to disengage from the seat;maintaining the member disengaged from the seat while compressed gasfrom the compressed gas storage unit enters the chamber; andcausing the mechanism to release the member such that the member becomesengaged with the seat, while the compressed gas expands within thechamber in an absence of combustion.

18. A method as in claim 17 further comprising providing a dischargevalve allowing selective communication between the chamber and a lowpressure side, wherein creating the residual pressure comprises closingthe discharge valve while the compressed gas expands within the chamber.

19. A method as in claim 18 wherein:

the discharge valve comprises a second member selectively moveable toengage a second seat; and

closing the discharge valve comprises causing a second mechanism torelease the second member such that the second member becomes engagedwith the second seat.

20. A method as in claim 17 wherein the chamber is defined by a pistonwithin a cylinder.

21. A method as in claim 17 wherein the chamber is defined by a rotatingelement enclosed within walls.

22. A method as in claim 17 wherein the member comprises a poppet.

23. A method as in claim 17 wherein the member comprises a plate.

24. A method as in claim 17 wherein the mechanism operates based uponmechanical principles.

25. A method as in claim 17 wherein the mechanism operates based uponhydraulic or pneumatic principles.

26. A method as in claim 17 wherein the mechanism operates based uponmagnetic principles.

Valve embodiments as described herein may be particularly suited tocontrolling flows of gas within systems employing compressed gas as astorage medium as described in the '223 Publication. However such valvesmay be employed in other applications calling for the control of fluidflows. Moreover embodiments are not limited to use in conjunction withgases, and alternatively may be used to control flows of other types offluids, for example liquids.

What is claimed is:
 1. An apparatus comprising: a cylinder configured toreceive a piston and defining a first port; a mechanical linkagecomprising a piston rod configured to transmit out of the cylinder, apower of gas expanding against the piston; an element configured toeffect gas-liquid heat exchange with gas in the cylinder in an absenceof combustion; and a first valve comprising, a first valve elementmoveable relative to the first port, a second valve element selectivelyrotatable relative to the first valve element to control a duration ofopening of the first port, and a third valve element selectivelymoveable to control a starting point of opening of the first port.
 2. Anapparatus as in claim 1 further comprising an actuator in communicationwith the third valve element.
 3. An apparatus as in claim 2 wherein theactuator comprises a stepper motor.
 4. An apparatus as in claim 2wherein the actuator is in communication with the third valve elementvia a rotating shaft.
 5. An apparatus as in claim 4 wherein the rotatingshaft is in communication with a gear.
 6. An apparatus as in claim 4wherein the rotating shaft comprises a pinion shaft.
 7. An apparatus asin claim 1 wherein the first valve further comprises a spring.
 8. Anapparatus as in claim 1 wherein the first valve further comprises apivot arm.
 9. An apparatus as in claim 1 wherein the second valveelement comprises a plate.
 10. An apparatus as in claim 1 wherein thethird valve element comprises a plate.
 11. An apparatus as in claim 1further comprising a physical connection to coordinate actuation of thefirst valve with the piston.
 12. An apparatus as in claim 11 wherein:the mechanical linkage further comprises a crankshaft; and the physicalconnection comprises a gear off the crankshaft.
 13. An apparatus as inclaim 12 wherein the gear is phase displaceable.
 14. An apparatus as inclaim 1 further comprising a control system comprising a VariableFrequency Oscillator (VFO) and configured to control a timing of thefirst valve.
 15. An apparatus as in claim 1 further comprising a controlsystem configured to control a timing of the first valve to determine avolume of gas for expansion in the cylinder.
 16. An apparatus as inclaim 1 further comprising a control system configured to control atiming of the first valve based on a sensed parameter.
 17. An apparatusas in claim 1 further comprising a control system configured to controla timing of the first valve based on a phase lock loop.
 18. An apparatusas in claim 1 wherein the first valve is actuable to place the cylinderin fluid communication with a high pressure side.
 19. An apparatus as inclaim 18 wherein the mechanical linkage is in selective communicationwith an energy source to compress gas within the cylinder.
 20. Anapparatus as in claim 19 further comprising a control system configuredto open the first valve where a built-up pressure in the cylinder nearsa pressure on the high pressure side.